1. Field of the Invention
The present invention relates to an optical waveguide and to a production method thereof. More particularly, the present invention relates to an optical waveguide made by using polymer material and to a production method thereof
2. Description of the Prior Art
An optical waveguide is widely used to optically connect a plurality of optical devices. In recent years, various attempts on the forming of this optical waveguide from polymer material to enhance the workability and the mass production have been considered.
For example, JP Laid-open (Unexamined) Patent Publication No. Hei 10-268152 proposes that photosensitive resin in liquid form, such as epoxy oligomer and acrylic oligomer, is coated over an under clad layer, then is exposed to light through a mask, and then is developed with solvent, to form a pattern into a core layer.
However, since the photosensitive resin mentioned above is in the liquid form before it is exposed to light, a given space must be formed between the mask and the photosensitive resin for exposing the coated photosensitive resin to light. For example, as shown in FIG. 6 of the publication cited above, a spacer is interposed between the mask and the photosensitive resin to define a space therebetween.
However, the interposition of the spacer therebetween requires increased number of processes and time-consuming and complicated works, making it hard to provide increased production efficiency.
Further, the photosensitive resin in the liquid form provides the disadvantages that the mask can be contaminated by the resin in the handling and that owing to the fluidity of the resin, the optical waveguide cannot be defined therebetween in a stable form.